Diesel or Outboard Engine Maintenance

I was aboard a friend’s boat the other day when suddenly his small inboard diesel starting sending up plumes of white exhaust. We looked over the side and saw that there wasn’t any cooling water coming out of the exhaust. Clearly the engine was overheating, but why? Once we shut it down, my buddy checked the sea strainer to see if it was blocked by debris. It had some debris in it, but not too bad. After cleaning it out, we restarted the engine again and this time slightly more cooling water was exhausted, but it still wasn’t normal. We suspected that either the through-hull intake was blocked or the impeller on the water pump was broken. Not having diving equipment or the courage to pull the hose off from the through-hull and risk sinking the boat while we poked around, we opted to check the impeller first. To my amazement, he admitted it hadn’t been changed since he purchased the boat 6 years ago. His philosophy was that it was working fine, why mess with it. Granted he had tools and spare parts onboard, but I was dumbstruck by the laissez-fair attitude toward engine maintenance.

Whether your boat has twin turbo diesels, an inboard kicker, or outboard engines, there are simple maintenance tasks that you can do to help keep your engine(s) dependable, your costs down, and your time adrift to a minimum. I recommend that you become familiar with your engine by referring to the owner’s manual. If you are a bit more adventurous, purchase and review the shop manual. Either will give you the manufacturer’s suggested maintenance tips while orienting you to where and what things are. Even if you have a pro maintain your engine, the basic knowledge in these publications will serve you well when talking to your mechanic.

My suggestions toward engine maintenance are straightforward and proactive. Keep the engine and engine compartment clean so you can see if you have any obvious leaks. Keep appropriate tools and spare parts aboard. Visually check your engine for clean and tight battery connections, cracked hoses, worn belts, rusty fittings or other signs of age. Keep your fuel clean and check your Racor or other fuel filters regularly. Check the engine oil level and ensure that coolant water is exhausting in proper quantities before leaving the dock.

My preference and a practice we followed in the boatyard when laying a boat up for any extended period is to run fuel stabilizer through the engine and top up fuel tanks to reduce condensation. Flush coolant water and replace with anti-freeze in cold climes. Change oil, filters, zincs, and yes, water pump impellers, annually and follow manufacturer’s recommendations on the rest. Unlike my friend, an ounce of prevention will keep you from being adrift at the worst possible moment.


f you’re getting your boat ready to sell, a moderate amount of time and effort will add genuine value and help justify your asking price.
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